package com.emergency.util;

import org.springframework.core.io.ClassPathResource;

import javax.servlet.http.HttpServletResponse;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

public class ShowUtil {

    public static void showPic(HttpServletResponse response) {
        try {
            OutputStream out = response.getOutputStream();
            response.setStatus(HttpServletResponse.SC_OK);
            //得到图片的二进制数据，以二进制封装得到数据，具有通用性
            ClassPathResource resource = new ClassPathResource("confirm_ok.png");
            byte[] byts = readInputStream(resource.getInputStream());
            out.write(byts);
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static byte[] readInputStream(InputStream inStream) throws Exception {
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        //创建一个Buffer字符串
        byte[] buffer = new byte[1024];
        //每次读取的字符串长度，如果为-1，代表全部读取完毕
        int len = 0;
        //使用一个输入流从buffer里把数据读取出来
        while ((len = inStream.read(buffer)) != -1) {
            //用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度
            outStream.write(buffer, 0, len);
        }
        //关闭输入流
        inStream.close();
        //把outStream里的数据写入内存
        return outStream.toByteArray();
    }
}
